Photons

This apparatus is designed to determine the approximate value of Planck's constant, using a range of LEDs of known wavelength, to allow the electron/photon energy to be calculated. There are LEDs, covering the light range from deep blue at 470 nm to near IR at 940 nm, mounted on box with 4 mm sockets for attachment to voltmeter and ammeter for voltage and current measurements. By monitoring the voltage at which each LED just begins to emit light, graph of energy input as function of light emitted frequency can be plotted and an approximate value of Planck's constant can be deduced. Requires a 9 DC power supply (standard lab power supply).